Extranodal non-Hodgkin lymphoma that occur in the gastrointestinal tract, salivary and thyroid glands, lungs, ocular adnexa, thymus, breast and occasionally other organs.
World health organization classification of gastric Mucosal associated lymphoid tissue lymphoma is a form of marginal zone lymphoma, a heterogeneous group consisting of extranodal MALToma, nodal marginal zone lymphoma and splenic marginal zone lymphoma.
Gastric MALToma occurs along the areas of lymphoid tissue in mucosal sites and is classified into gastric and non-gastric types.
Gastric marginal zone lymphomas are characterized by an antigen driven transition from normal to malignant marginal zone B cells.
Gastric MALToma typically develops in the stomach with Helicobacter pylori infection playing a major role in the pathogenesis of the disease.
Eradication of H. pylori can cause tumor regression.
Immunophenotypes associated with marginal zone lymphoma is CD5 negative, CD10 negative, CD20 positive, CD23 positive and negative, CD43 positive and negative, cyclin D1 is negative for BCL-2.
The t (11; 18) (q21;q 21) chromosomal translocation is the most common found in gastric MALToma and accounts for 18-53% of cases.
The above translocation is associated with antibiotic resistance, and is related to disseminated disease.
Some MALToma can transformed into diffuse large cell B-cell lymphoma.
Gastric MALToma usually has a indolent course with dyspepsia the most common symptom.
Gastrointestinal bleeding is rare with gastric MALToma.
Diagnosis requires endoscopic assessment, testing for the presence of H. pylori, and clinically appears similar to chronic gastritis or peptic ulcer disease.
Endoscopic ultrasound can determine the depth of invasion into the gastric wall.
Complete assessment of gastric MALToma requires CAT scans of the abdomen chest and pelvis and bone marrow biopsy.
Treatment for gastric MALToma includes antibiotic eradication of H. pylori, use of a proton pump inhibitor, unless t(11; 18) translocation is present and that will require alternative treatment.
All therapies include involved field radiation therapy, rituximab, or chemoimmunotherapy.
Involved field radiation is considered for patients with lesions that extend into the muscularis layer or 2 adjacent organs.
Reevaluation with endoscopy at 3 month intervals is appropriate surveillance management.
MALToma can arise in stomach, salivary glands, lung, small bowel and represent 5% of all cases of non-Hodgkin’s lymphoma.
MALToma of the stomach is the most common primary gastrointestinal lymphoma worldwide.
Extranodal marginal zone lymphoma also known as low grade B cell lymphoma of mucosa associated lymphoid tissue.
A type of B cell marginal zone lymphoma.
Mucosa-associated lymphoid tissue (MALT) represents 7-8% of B cell lymphomas.
Gastric MALTomas comprise almost 50% of all such lesions.
Macroscopically such lesions are often indistinguishable from inflammatory lesions, but can also present with obvious tumor masses.
Lesions are often, multifocal.
Hallmark of disease is indicated by infiltration of tissues of parenchymal epithelium with lymphoepithelial lesions with centrocyte-like or small lymphocytes in a parafollicular distribution of B cells.
B cells can infiltrate and disrupt mucosal crypts and glands.
Immunohistochemical testing is positive for CD20 and positive or negative for bcl-2.
Arises in context of pre-existing prolonged lymphoid proliferation in mucosal sites.
Protein bcl-1 is universally negative.
Associated with a indolent course and usually remains localized to the primary extranodal site of disease.
Monoclonal B cell proliferation in and around mucosal tissues.
The presence of a chromosomal translocation t(11,18 in gastric MALToma suggests that eradication of H. pylori is unlikely to result in remission, and that in such cases radiotherapy is the most effective therapy and should be administered without the delay.
Rarely arise in tissues with mucosal associated lymphoid tissue but rather arise in tissues modified by inflammation associated with Helicobacter pylori infection of the stomach or bronchiectasis of the lung.
Mucosa-associated lymphoid tissue lymphoma B cell tumor of the stomach in the presence of Helicobacter pylori can be treated 80% of the time with eradication of the infection.
The presence of H pylori in 92% of patients with primary low-grade gastric MALToma.
Primary MALToma of lung incidence is 0.49% of NHL.
Marginal zone B-cell lymphoma, a peripheral B cell neoplasm.
Typically express pan B antigens (CD19, CD20, CD22, CD79a) and lack CD5, CD10, CD23, and Bcl-1 expression.
Rarely CD5 positive and associated with more aggressive clinical course.
36% of patients with newly diagnosed disease have a serum monoclonal gammopathy.
Plasmacytic differentiation associated with paraprotein production, advanced disease and involvement of lymph nodes and bone marrow.
Extranodal marginal zone lymphoma that remains localized for an extended period, lacks prognostic features, and has a superior 5-year survival of 81% and failure free rate of 65% compared to its marginal zone nodal counterparts.
Lymphoid tissue involved may be present at the site of origin or may be acquired associated a result of chronic inflammation or an autoimmune disorder.
Occur in chronic inflammatory processes such as Sjogren’s syndrome, Hashimoto’s thyroiditis and possibly interstitial pneumonia.
Can transform into a more aggressive process, usually diffuse large cell lymphoma.
Lesion characterized by an infiltrate of centrocyte like cells, which are small to medium sized lymphocytes with abundant cytoplasm and irregularly shaped nuclei, with a few transformed blasts.
Nonmalignant reactive follicles often seen on histopathologic findings.
Significant feature is the presence of lymphoepithelial lesions with invasion and damage to mucosal glands and crypts by tumor cells.